


Mobius Strip

by dirigibleplumbing



Category: The Avengers (Marvel Movies)
Genre: Alternate Universe - Canon Divergence, Angst with a Happy Ending, Avengers: Endgame (Movie) Spoilers, Fix-It, Frigga (Marvel) - Freeform, M/M, Post-Avengers: Endgame (Movie), Pre-Slash, Steve Rogers gets a life, Suicidal Thoughts, The Ancient One (Marvel) - Freeform, Time Travel, ignores Tony/Pepper
Language: English
Status: Completed
Published: 2019-04-29
Updated: 2019-04-29
Packaged: 2020-02-09 22:18:01
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,648
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18647188
Author URL: https://archiveofourown.org/users/dirigibleplumbing/pseuds/dirigibleplumbing
Summary: Steve sets off to return the Infinity Stones. It ends up not being quite as straightforward as he'd imagined.





	Mobius Strip

**Author's Note:**

> Endgame spoilers. There are no archive warnings in order to avoid spoiling the movie through warnings. Other than the character deaths of the movie, the only warning is for some somewhat brief and not particularly detailed suicidal thoughts. If I have missed any further warnings, I apologize and will correct them! 
> 
> I have only seen Endgame once and may have mis-remembered certain things. If you see a mistake that can be fixed in 5 minutes or fewer, don’t hesitate to let me know in a comment here or via Tumblr message. If it’s more complicated than that, please leave me in blissful ignorance. 
> 
> This is a fill for a picture square on my Stony bingo card, which shows Steve hunched over as if in despair. 
> 
> Un-betaed. All mistakes my own.

“Thank you, Captain,” the Ancient One says when Steve reaches the roof of the New York Sanctum in 2012.

He’s not sure how to reply—if she’s thanking him for saving the universe, or returning the Stone—so he just opens the silver case he’s carrying and watches the green gem float up from it. Her hands form a decisive gesture and her necklace slots open, allowing the Stone to settle inside it before closing up again.

“For volunteering to join me as we work to restore this timeline,” she says simply.

Steve snaps the case shut. “I—”

“Dr. Banner passed onto you my stipulations for giving him the Stone?” she asks, already starting the motions that Steve now recognizes create a portal.

“The Time Stone, yes—”

“In your team’s efforts to recover the Tesseract, this time’s Loki disappeared with it. I’m sure you haven’t forgotten.”

Steve glances warily at the panorama on the other side of the glittering golden circle she’s formed. There are trees with fuchsia trunks and branches, flying metal pods shaped like horse-drawn carriages without horses, house-sized buildings made of tangerine-colored clay, and a sea of stars in a violet sky.

The Ancient One turns her snakelike face toward him, her wide, lashless eyes meeting his. “Steve,” she says, for the first time using a tone of voice that’s almost gentle rather than singsongy confidence, “if I am not successful in bringing Loki to Stark Tower at the time he vanished, you will not be able to return to the place you’ve come from. This timeline will branch and never become the one that you just left.”

Steve swallows. “Who says I gotta go back?”

Her mouth quirks up on one side in a small, knowing smile. “You’ll at least stop there long enough to assure your friends that you’re alright and were successful in your mission.”  

She’s right. And, well, what else is he going to do?

They step through the portal to the alien landscape.

They end up only staying on the planet long enough to rent a spaceship. On their way out of the system, they encounter a herd of whale-like creatures each the size of Stark Tower, which feed on radiation emitted by the engines of most spaceships. At one point, they track Loki to an alien arboretum and Steve fights what he thinks might be a carnivorous flower. They stop at a drive-thru—fly-thru?—restaurant that orbits a large asteroid and Steve drinks something that reminds of him of a milkshake, a cheesecake, and a live eel all at once. A wizard with jade-colored skin recognizes the Ancient One and pledges themself to assisting in their quest to return the timeline to a form closer to its original arrangement.

And that’s just the first day.

It gives him less time to dwell on things, that’s for certain.

After the first time she takes him into the Mirror Dimension, Steve says it reminds him of M.C. Escher.

“A slow, but dedicated student of the mystic arts,” the Ancient One says. “Though his precision in casting had phenomenal results when he finally mastered the process.”

“You taught Escher?”

“For a time, yes. There are spells worked into many of his prints.” She turns to him, a blank, benign expression on her face. “You are a student of art. And now a traveler across time and dimensions. Surely you see how he worked to capture the five-dimensional in a medium that contains only two.”

Steve pictures a single staircase going both up and down and in a circle, and thinks he actually knows what she means this time.

He doesn’t know if wizards need sleep or to meditate or how they take their rest, but each day when his wrist tells him that it’s nighttime in New York, the Ancient One comes and says that it's time for a break and Steve lays down in his small quarters on the spaceship and tries to sleep.

The first night, he gives up quickly and does push-ups and sit-ups and jumping jacks for hours, watching the void of distant stars and planets swim past the portholes, until even his superpowered muscles give out and he sits, hunched and trembling, on the floor. The ache and tremors in his body numb the pain of his thoughts—a cycle of _it was supposed to be you, he had so much to live for, you promised him_ —but don’t blot them out entirely, and he never falls entirely asleep. It’s hours before sunrise in New York when he gets up, his joints now protesting at how long he’d stayed crouched and clinging to himself, and heads to the ship’s bridge to check their progress on tracking Loki.

The second night he lies in bed and doesn’t get up, even when he realizes he’s clutching the blanket so tightly he's torn holes in it. For five years Steve made a life of telling people to move on while avoiding doing so himself. But what does he have to move on to? He feels like when he first woke from the ice, and only wanted to go backwards.

Like he is now, being in 2012. It doesn't escape him that as soon as he had the chance, he returned to a place where Tony is alive; he's on Earth now, working on rebuilding New York. He has a future ahead of him, a future Steve knows nearly as well as his own past, one of pain and loss and betrayal. Steve can't interfere with it, as much as he wants to. 

The third night, he asks the Ancient One to cast a spell to help him sleep. When she does, he dreams of Chitauri leviathans and of outliving everyone he’s ever cared for.

She helps him sleep every night for the rest of their journey.

When they return to Manhattan with a petulant Loki and two versions of the Space Stone in tow, the Ancient One ends up only needing to send them back six days to get Loki to when and where he should be.

They leave the Mind Stone with him too. No one thinks to ask why it’s no longer part of his Scepter. Sitwell and Rumlow are there when Clint and Hulk arrive to subdue Loki, and Steve thinks he can see it on the agent’s faces when they decide that the Hydra Captain America they met was the trickster, too.

Now Steve watches through the glass walls of Stark Tower as Tony and Thor argue with Pierce and SHIELD about who should get jurisdiction of the newly recaptured Loki and the Stones. His heart twists with an ache he can’t quite name.

“Your counterpart won’t remember what you said to him,” she says, tone mild. “Not consciously, anyway.”

Steve just nods. He can’t tear his eyes away.

“Onto your next drop-off, Captain?”

He doesn’t think she’s just saying that to remind him that if he stays too long, he could create another branching timeline. He’s learned over the last few days how to tell when her words belie a deeper meaning, though not how to interpret her true intent or message. “Yes,” he says.

He can feel her eyes on him. He doesn’t know if it’s just the regular impression of being watched, or something she’s doing with magic.

He wonders what she sees, when she looks at him—whether with a sorcerous Sight or simply the eyes of age and experience—but doesn’t want to know her conclusions.

“It’s not what you think it is,” she warns.

At last Steve turns to face her. “What isn’t?”

“Your life,” she says simply. She nods at him. “The life you get. Goodbye, Captain.”

Like that, she’s gone. She doesn’t make a portal that he can see, or fade, or blink out. She’s simply absent where she was once present.

Steve swallows and makes for his next stop.

 

* * *

 

This trip to 1970 is much less risky than the first. He’s prepared this time, with a uniform he didn’t have to steal, plus a photostatic veil and fake documents for a low-ranking SHIELD agent whose recent death had not yet been recorded.

He gets inside Camp Lehigh just in time to see himself and Tony departing. He was supposed to arrive five minutes later. His recall is perfect and he and Bruce went over the details of the mission several times; it’s not an accident that he has time to watch Tony sling an arm around his past self, gesturing with his briefcase as he speaks.

The camp is on high alert after an agent reported seeing two infiltrators—the versions of Steve and Tony who have just left with the Tesseract and Pym particles—but Steve’s disguise does the trick.

When he’s returned the Stone and the fresh vials of Pym particles Hank supplied him with, he finds a trainee pushing a mail cart down a familiar hallway of offices.

“I’ve got this,” Steve says, taking hold of the cart.

The trainee is visibly confused. “But I—”

“It’s all taken care of, just take a break. Director’s orders.”

The young man swallows visibly, his eyes darting in the direction of Peggy’s office. Then he nods and takes off in a near-sprint.

He’s probably reporting Steve, too, just in case the order didn’t really come from her, but Steve’s not worried.

He doesn’t turn off the photostatic veil. He just hands Peggy’s assistant her mail.

Peggy glances up from her desk. “Thank you,” she says with a polite smile, then returns to her paperwork.

He watches her until her assistant clears his throat, clearly wondering why Steve is lingering.

He dashes away before anyone has time to realize he shouldn’t be there.

 

* * *

 

Steve has been looking forward to seeing Asgard. He never thought he’d get a second chance to visit Thor’s first home.

The palace is on alert too, following Thor and Rocket’s appearance, and Steve is less confident in its bejeweled, golden halls than he’d been in the familiar military drab of Camp Lehigh. He has the floorplan memorized, though—and of course, then Frigga finds him.

“I’m pleased to finally meet you, Steve,” she says, and Steve thinks about how—by returning Loki to New York in 2012 in order to be brought to Asgard, where he is now, in this present—he’s contributed to the circumstances of her death.

Once again, Steve covers his discomfort by opening the case containing the remaining Stones.

She places a quelling hand on his. “Time isn’t what people say it is,” she says, and Steve can swear there's a new Irish lilt to her voice, is sure that if he were capable of raising his stinging eyes to her face he’d see not one of an ancient, eternally youthful Asgardian queen, an _all-mother_ , but of a tired, bereft immigrant whose son will surely take further ill and die before he is even a man—but he’s not capable, so he just lets the warmth of her hand on his engulf him. “When Loki was first lost to me, I began embroidering a tapestry all over in vines, with rosebuds just about to bloom. But in my sorrow, I worked slowly. When I had begun, it was the end of winter, and flower buds were just beginning to peek through the melting snow. By the time I finished, more than a year had passed. It was summer, and Loki was alive after all—but not the man I thought I knew. When I saw the complete work, I realized that they should have been full summer flowers all along. I spent days carefully pulling out every stitch of every budding rose and replacing them with open blooms.”

Frigga drops her hand and Steve, knowing what he’ll see now, dares to look up at her. As he expects, she is herself, adorned in Asgardian silks and armor. “No one who saw the final result would know, to look at it, that the roses had once been buds,” she continues. She waves her hand, and the Ether flows up from the open case to meet it, like a teapot being poured in reverse. “But I would always know. In order to sew the blossoms, I had to cut and tear and discard the thread that had made the buds, just as I had to sew them in the first place. Both had to happen for this to happen.”

She dances the fingers of her other hand in the air, as if plucking an invisible harp, then twists her wrist, plucking a cut rose out of thin air. After she hands it to him, she turns and strides away without saying anything else.

Steve looks at the rose. It’s more than a bud, but not fully open, either. Its petals seem almost heavy with pigment, and the thick scent that emanates from them is syrupy. They are the same blood-red as the Stone he has just returned.

He grips the stem tighter—too tight, surely, he realizes too late, tight enough to burst the capillaries of the plant—but instead of crushing it, he pricks his finger on a thorn instead and reflexively loosens his grip. The cut doesn’t bleed.

The footsteps of guards approaching from the next hallway hurry him on to his next destination.

 

* * *

 

When Clint said there was a “red guy” on the cliffs of Vormir, it hadn’t occurred to Steve that it would be Schmidt. Clearly, it hadn’t to Clint, either.

“At last,” the hovering figure intones. “The source of my downfall and the reason for my imprisonment comes to treat with me.”

Steve could blame the Red Skull for the years he spent frozen, for so many of the losses he suffered. Bucky’s fall, certainly—and standing on this ledge now, it’s easy to see himself in Bucky’s place, on a snowy mountainside train worlds and lifetimes away—but he finds there are some things he’s moved on from, after all.

“If I jump,” Steve says slowly, “would Nat come back?” It would create yet another branching timeline but—but there should be more of those where she’s alive, even if he isn’t, he thinks.

“No,” Schmidt pronounces heavily.  

“That’s all I need to know.” Steve pushes past him and drops the Stone over the edge without ceremony. There’s nothing he can see of Natasha’s body.

“You will face me and—” Schmidt begins.

“Just—shut up,” Steve snaps.

He ignores Schmidt’s gaping and blustering as he turns to go. Steve has nothing to say to say to Schmidt, and Schmidt is incapable of saying anything Steve cares to hear.

 

* * *

 

Bruce, Hank, and Jan tried to explain to Steve what he might find when he came to Morag. All that Steve had gleaned from their explanations was that they weren’t entirely sure.

The scenario should have been that it would be a simple question of timing, of finding the small window of time between Quill waking up from Nebula and Rhodey knocking him out and Korath the Pursuer and his team of Sakaarans arriving to intercept him on Ronan’s behalf.  

And, well. That is what Steve finds, at first.

But afterward, while Quill awakens and takes the Stone with a suspicious glance followed by a pleased shrug, Steve's time travel device stops working.

Or—something. The interface seems the same, but when he puts in the information and dates the way he has all the while, the way Tony made them practice over and over again, nothing happens. He almost expects an error message. _404, time not found_ , he thinks wildly.

Quill’s run-in with Korath and his team begins to unfold. Steve’s hiding place is not, strictly speaking, a good one. It was only meant to obscure him from a distracted, newly awakened Quill for a few minutes, not a group of on-edge combatants whose fight is rapidly approaching Steve’s position.

With a detachment part of him knows should be horror, it dawns on him what that error message, if it existed, would really say.

It’s like the Ancient One was trying to tell him about Loki. In the past of the Steve here now, the Steve who watched Thanos and his armada turn to dust and attended Tony’s funeral and stepped onto the time platform to return the five Stones, Quill got the Reality Stone, was intercepted by Korath, and then later pursued by Gamora, Nebula, and Ronan, each actors with varying degrees of separation from Thanos’ orders.

But that past isn’t the one he’s in right now. He’s in the past where Rhodey and Nebula came to Morag, took the Stone, and Steve returned it—and where that second Nebula’s implants alerted Thanos to their plans, bringing him to Earth years later to face the full might of the Avengers.

Where and when Steve is now, there is no Thanos, Gamora, or Nebula. Without the players needed to make it exist, there’s no way to get to that future from here.

Or, it seems, anywhere else.

Hurried footsteps are approaching his position. He shuffles the date and time in frustration, just to see if anything, any random combination will work.

It locks in place all at once, and then he’s jumping through time.

 

* * *

 

He’s still on Morag, and is that—he knows that ship.

Steve runs toward it. “Rhodey! Nebula!” he yells.

“What the hell?” Rhodey asks as Steve reaches them. “How’d you get here? Something go wrong?”

“I don’t really have time to explain. Nebula, the you from this time—you’re on the same network, you have to disable it or Thanos—”

Nebula’s head telescopes out into several puzzle-piece panels. She reaches under one to a compartment, grasps onto a small panel, and rips it violently out, making sparks. Her eye twitches and she stumbles as one of her legs gives out. “Done,” she growls.

“Uh, you okay?” Rhodey asks.

“Fine.” She bends her neck sharply to the side and then upright again, making it pop. The curved panels pop back into place on her skull. “Tony can fix it later.”

And Steve—he can’t think about that, he can’t think about what he’s going back to. Right now it’s a matter of whether he can get anywhere at all. He focuses his attention on his wrist band and starts entering his return trip. Rhodey had been able to leave, the first time, but Nebula hadn’t at first. Because of the paradox, he imagines. But he’s just created another one. Hasn’t he?

He punches it and starts going—somewhere.

 

* * *

 

Steve reappears on the time platform on a sunny afternoon by the Hudson River. Sam and Bucky are there to greet him, with Bruce at the controls.

“How’d it go?” Bruce asks.

“Fine, I think,” Steve says without thinking. “I returned them, and I’m back, so it must all be one timeline, right?”

Bruce hums thoughtfully as he starts shutting everything down. “We’ll figure it out when we do the whole team debrief.”

“Who are we counting as the ‘whole team’ these days?” Steve asks, accepting Bucky’s hand as he steps down from the platform.

“Good question,” Bruce replies with a chuckle.

“Where are you off to?” Sam asks, coming up on Steve’s right, Bucky on his left.

Steve leads them toward the main compound building, which is just as he last saw it—rebuilt the same as before, and almost, but not quite, home. “Just need some time on my own,” he says. “I’ll catch you later, okay?”

“He won’t be back until late tonight, at least,” Bucky says him, something playful and knowing in his voice.

It sounds like—but he can’t mean that. Steve stops in his tracks. “Who?”

Bucky rolls his eyes. “Stark. He’s picking up Princess Shuri in Manhattan and taking her out to dinner before they start trying to put Vision back together again.”

“Steve?” Sam grips Steve by the arm. “You good, man?”

Steve feels light-headed, actually. He might have been swaying on his feet before Sam grabbed him. “Bruce,” he says, “what happened after you used the Gauntlet to bring everyone back?”

Bruce tells him.

It's not the same afternoon that Steve left. The date is the same, the sunshine, the birds and mosquitoes and smell of cut grass—but little else is. Nebula's implants didn't tip off Thanos. He and his armada never came to this present. There was no battle. And Steve is here anyway.

Both had to happen for this to happen.

And all of that means—that means—

Tony never used the Gauntlet. He’s alive.

And he’s coming back tonight.

 

* * *

 

Steve barely gets a chance to exchange a word with Tony when he and Shuri whirl inside like a hurricane of technobabble, Bruce padding more calmly alongside.

Steve and Wanda watch the three scientists work from outside the workshop. Shuri does most of it, while Bruce observes and Tony has Friday take copious notes about vibranium. Steve leaves twice to bring everyone coffee, and returns with pastries the second time.

The sun is coming up when Tony, Shuri, and Bruce step out. “Is it him?” Wanda asks.

“He’s just waking up,” Bruce says softly. 

Wanda nods and gazes through the glass wall into the lab. Steeling herself, she opens the door and walks through. Friday tints the glass to give them full privacy. 

Bruce offers to show Shuri to her quarters, leaving Steve standing in the hallway, staring at Tony. At Tony’s life, bubbling out of him, from the sparks in his eyes to his fluid hands as he stuffs them in his pants pockets.

“What’s up?” Tony asks, bouncing on his heels.

“Can I take you out for breakfast?” Steve asks.

Tony looks at him for some time. His eyes scroll over Steve’s face like he’s reading words written across it. Finally, he breaks out into a crooked grin and says, “Sure.”

 

**Author's Note:**

> Yeahhh it didn't escape my notice that by changing the timelines to get Tony back, we don't get Gamora back. Not sure how I feel about all of these doomed-to-soon-die ancient women being the dispensers of wisdom, either, but I'm trying to work with canon here. 
> 
> When Red Skull showed up in Infinity War, I hoped his appearance hinted that he and Steve would meet again. Hopefully it will be Captain America Sam Wilson who encounters him instead, because as you can see from this piece, my favored response to Nazi ramblings is: "Man, shut the hell up!" 
> 
> I am realllly into time travel mechanics, in case you couldn't tell! I know the MCU's explanation is that you can change the chronological past without impacting the future you came from, because even if it's the chronological future, it's in your past and it already happened to you, so the “past” you've changed just makes a new timeline. But how do you travel between one timeline and another? The stance of this story is that you can't, unless you've changed the timeline you're in into the one that's your destination. Therefore, in order to return to the time and place he left to return the Stones, Steve had to direct each timeline he visited into a shape that matched his original one. The final timeline is unified yet still has a paradox in it—it's just one that sort of self corrects through the events of this story, hence the title. 
> 
>  
> 
> [Tumblr post](https://dirigibleplumbing.tumblr.com/post/184533546592/mobius-strip-dirigibleplumbing-the-avengers) for the fic. 
> 
> Find me [on Tumblr](http://dirigibleplumbing.tumblr.com/).


End file.
